Role of self-organization, nanostructuring, and lattice strain on phonon transport in NaPb{sub 18-x}Sn{sub x}BiTe{sub 20} thermoelectric materials.

Journal Article · Mon Nov 16 04:00:00 EST 2009 · J. Am. Chem. Soc.

DOI:https://doi.org/10.1021/ja905448b· OSTI ID:1008304

He, J; Gueguen, A; Sootsman, J R; Zheng, J -C; Wu, L; Zhu, Y; Kanatzidis, M G; Dravid, V P ^[1]

---

1. Materials Science Division

The composition and microstructure of five thermoelectric materials, PbTe, SnTe, Pb{sub 0.65}Sn{sub 0.35}Te and NaPb{sub 18-x}Sn{sub x}BiTe{sub 20} (x = 5, 9), were investigated by advanced transmission electron microcopy. We confirm that the pure PbTe, SnTe, and Pb{sub 0.65}Sn{sub 0.35}Te have a uniform crystalline structure and homogeneous compositions without any nanoscale inclusions. On the other hand, the nominal NaPb{sub 9}Sn{sub 9}BiTe{sub 20} phase contains extensive inhomogeneities and nanostructures with size distribution of 3-7 nm. We find that the chemical architecture of the NaPb{sub 13}Sn{sub 5}BiTe{sub 20} member of the series to be more complex; besides nanoscale precipitates, self-organized lamellar structures are present which were identified as PbTe and SnTe by composition analysis and transmission electron microscopy image simulations. Density functional theory calculations suggest that the arrangement of the lamellar structures conforms to the lowest total energy configuration. Geometric-phase analyses revealed large distributed elastic strain around the nanoscale inclusions and lamellar structures. We propose that interface-induced elastic perturbations in the matrix play a decisive role in affecting the phonon-propagation pathways. The interfaces further enhance phonon scattering which, in turn, reduces the lattice thermal conductivity in these systems that directly results directly in improvement in the thermoelectric figure of merit.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC; ONR; Keck Foundation; State of Illinois
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1008304
• Report Number(s): ANL/MSD/JA-69086
• Journal Information: J. Am. Chem. Soc., Journal Name: J. Am. Chem. Soc. Journal Issue: 49 ; Nov. 16, 2009 Vol. 131; ISSN 0002-7863
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
ARCHITECTURE
CONFIGURATION
DISTRIBUTION
ELECTRONS
FUNCTIONALS
MICROSTRUCTURE
NANOSTRUCTURES
PERFORMANCE
PHONONS
SCATTERING
STRAINS
THERMAL CONDUCTIVITY
THERMOELECTRIC MATERIALS
TRANSMISSION ELECTRON MICROSCOPY
TRANSPORT